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DESCRIPTION: Main riser cover Velcro® replacement.
AUTHORIZED REPAIRMEN: FAA Senior or Master Parachute Rigger
MATERIALS: E thread—color to match
Velcro®—color, width, and type to match
MACHINES: 301 Straight Stitch—Medium Duty 7-11 SPI
EQUIPMENT:
Scissors
Seam ripper or scalpel
Marking pencil
6" ruler
PROCEDURE
Note: The name Velcro® is a trade name for what is known as “pressure sensitive hook and loop fastener.”
It is a commonly used material for closure systems. Before the advent of Velcro®, snaps and
zippers were the preferred method of closing containers. Velcro® changed how the parachute industry
designed products. In the late 1970s and early 1980s, there was a tendency to overdo the use of
Velcro® and problems with durability and interaction with other materials became known. Since
then, the use of Velcro® has been reduced to those applications where it is superior to other methods
and can be easily replaced.
1.0 DISASSEMBLY:
1.1 Identify the nature of the use of the Velcro®. Before you remove the piece, note how it is
attached to the container. Some designs are such that several layers of construction have to be
reversed to get to the location where the Velcro® was sewn on. If this is the case, the rigger
may have to make a very expensive repair to replace a small piece of Velcro®.
2.0 REASSEMBLY:
2.1 Cut the replacement Velcro® to size. Velcro® is normally scissor cut, not cut with a hot knife.
2.2 Position the Velcro® and stitch around the perimeter at .12" from the edge. For any pieces 1"
in width or wider, sew a row of stitching down the center [Figure A]. This prevents the
center from being pulled up from the material and loading the outside row of stitching
[Figure B].
2.3 Some applications have the Velcro® sewn to a piece of
tape for support. Again, if it is 1" or more wide, sew
down the center to prevent lifting.
2.4 Depending on the application, the mating loop piece
of Velcro® may be wider than the hook to provide
additional protection. That is, the hook may be .75"
wide and the loop 1" wide.
7-48
3.0 INSPECTION:
3.1 Check that thread tension is
correct.
3.2 Verify orientation is correct.
3.3 Check that center stitching is
used where needed.
7-49
Parachute Repair Procedure
TITLE: 7.2.4 Container Plastic Stiffener Replacement
NUMBER OF PAGES: 2
APPLICABLE PRODUCTS: All types of containers which use plastic stiffeners.
DESCRIPTION: Replacement of damaged plastic stiffeners of all types.
AUTHORIZED REPAIRMEN: FAA Senior or Master Parachute Rigger
MATERIALS: E thread—color to match
Grommets—size, type, and material to match
Plastic stiffeners—type and thickness to match
MACHINES: 301 Straight stitch—Medium Duty 7-9 SPI
308 Zigzag—Medium Duty 7-11 SPI
EQUIPMENT:
Scissors
Seam ripper or scalpel
Marking pencil
6" ruler
Grommet die set—Size to match grommets
Leather mallet
Grommet cutting board
Hole punch to match grommet size
Basting tip
Diagonal wire cutters—8" minimum
Heavy shears or tin snips
Electric drill & 3/8" drill bit
Feeler gauge—.010"
PROCEDURE
Note: The term “plastic,” when used in conjunction for the materials
used as stiffeners in modern parachute containers, is a misnomer.
In reality, the composition of the material varies. The most
common material used today is MDS nylon, molydisulfide nylon.
In addition, Lexan®, a clear polycarbonate material and HDPE,
high density polyethelyne, are also used. The most common thicknesses
used are .025", .040", and .060", which are standard commercial
thicknesses commonly available.
Stiffeners are used primarily as backing for grommets to spread the
load placed on closing flaps. Instead of focusing the load on the
diameter of the grommet, it is spread out across the length of the
stiffener, resulting in a smoother flap and container. Consequently,
replacing plastic stiffeners almost always requires replacing the
grommet as well. Usually the plastic breaks at the grommet location
because the hole for the grommet is the weak point. The following
procedure shows the replacement of the bottom main flap
stiffener of a Javelin container.
1.0 DISASSEMBLY:
1.1 Unpick the stitching that holds the binding tape to the bottom
flap [Figure A]. Remove the grommet.
1.2 Remove the stitching that holds the stiffener in position. Remove the stiffener.
　
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本文鏈接地址：Parachute Rigger Handbook(83)